In its June 13, 2001 report, "Stem Cells: Scientific Progress and Future Research Directions," the National Institutes of Health notes that immune rejection is a profound challenge in human embryonic stem cell transplantation. The report concludes that nucleus transplantation offers a viable way around this challenge because it can produce stem cells with genetic material identical to that of the patient. Simply put, cells derived from one's own tissues are less likely to be rejected. A report issued by the National Academies in September 2001 reached the same conclusion, and urged research on techniques to manipulate the genetic makeup of stem cells, including nucleus transplantation. 

Nucleus transplantation is the transfer of DNA from the nucleus of a "somatic cell" (skin, heart, nerve or anything or any other non-egg or sperm cell) into an egg that has had its nucleus removed. "Cloning," means to copy, whether one is copying a molecule, a cell or a collection of cells that make up a human blastocyst. 

Nucleus transplantation for the purpose of producing molecules or cell lines provides us with unique opportunities to develop effective treatments for a wide variety of currently incurable diseases and disorders. It is also a powerful tool of modern forensic science, vaccine development and drug discovery and testing.